Based on the specified subject context map being used to build a Subject instance, returns any previously
remembered principals for the subject for automatic identity association (aka 'Remember Me').
<p/>
The context map is usually populated by a {@link Subject.Builder} implementation.
See the {@link SubjectFactory} class constants for Shiro's known map keys.
@param subjectContext the contextual data, usually provided by a {@link Subject.Builder} implementation, that
is being used to construct a {@link Subject} instance.
@return he remembered principals or {@code null} if none could be acquired.
Based on the specified subject context map being used to build a Subject instance, returns any previously remembered principals for the subject for automatic identity association (aka 'Remember Me'). <p/> The context map is usually populated by a {@link Subject.Builder} implementation. See the {@link SubjectFactory} class constants for Shiro's known map keys.
@param subjectContext the contextual data, usually provided by a {@link Subject.Builder} implementation, that is being used to construct a {@link Subject} instance. @return he remembered principals or {@code null} if none could be acquired.